碱性阻挡层抛光液中ULK介质抛光性能的研究

研究了化学机械抛光(CMP)过程中抛光液的SiO₂磨料质量分数和表面活性剂对多孔SiOCH薄膜(ULK介质)介电常数(k)及抛光速率的影响。所用抛光液(pH=10)主要由0%~4%(质量分数,下同)SiO₂、0.075%H₂O₂、1%邻苯二甲酸氢钾和不同质量浓度的表面活性剂组成,其中表面活性剂为非离子表面活性剂脂肪醇聚氧乙烯醚(AEO-9和AEO-15)、阴离子表面活性剂十二烷基硫酸铵(ADS)和两亲性非离子表面活性剂辛基苯酚聚氧乙烯醚(OP-50)。结果表明,磨料质量分数的增大会使ULK介质的去除速率和k值都增大。聚醚类表面活性剂都能在CMP过程中很好地保护ULK介质表面,降低其去除速率,OP-50的效果尤其好。当采用2%SiO₂+0.075%H₂O₂+1%KHP+200 mg/L OP-50的抛光液进行CMP时,ULK介质的去除速率为5.2 nm/min,k值增幅低于2%,Cu和Co的去除速率基本不变。

Study on polishing performance of ULK dielectric film in alkaline polishing slurry

The effects of mass fraction of abrasive and different surfactants on the dielectric constant(k)and removal rate of porous ULK(ultralow-k)dielectric SiOCH film during chemical mechanical polishing(CMP)were studied.The slurry(pH=10)was mainly composed of 0-4wt.%SiO₂,0.075wt.%H₂O₂,1wt.%potassium hydrogen phthalate,and different mass concentrations of surfactant,which was a nonionic polyoxyethylene alkyl ether(AEO-9 or AEO-15),an anionic ammonium lauryl sulfate(ADS),or an amphipathic nonionic octylphenol polyoxyethylene ether(OP-50).The results showed that the removal rate and k value of ULK dielectric film were increased with the increasing of the mass fraction of abrasive.All of the used polyether surfactants,especially OP-50,could protect the surface of ULK dielectric film during CMP and reduce its removal rate.When CMP in a slurry composed of 2wt.%SiO₂,0.075wt.%H₂O₂,1wt.%KHP,and 200 mg/L OP-50,the removal rate of ULK dielectric film was 5.2 nm/min and its k value was increased by 2%below after CMP,while the removal rates of copper and cobalt were changed slightly.